1. Field of Endeavor
The present invention relates to microfluidic systems and more particularly to a hydraulically amplified microelectromechanical systems actuator.
2. State of Technology
U.S. Pat. No. 6,068,751 for a microfluidic valve and integrated microfluidic system to Armand P. Neukermans, issued May 30, 2000, provides the following background information, xe2x80x9cVarious efforts are underway to build miniature valves and pumps in silicon for micro-fluidics. It is however proving to be difficult to produce good sealing surfaces in silicon, and it turns out that these valves, although in principle mass-produced on a silicon wafer, become expensive in their packaged finished form. Consequently, such micro-fluidic components can hardly be considered inexpensive and/or disposable. Moreover, in such micro-fluidic components liquid contacts the valve and pump bodies and passages, thereby creating a contamination problem if the micro-fluidic component is to be reused. In addition, these micro-fluidic valves still must be interconnected into systems, and such interconnection also becomes expensive. This interest in micro-fluidic components has been s, purred largely by the rapid developments in the medical and biological sciences and related fields. In many such applications, small amounts of liquids need to be dispensed, samples need to be introduced and mixed in a given sequence with a variety of reagents, and the reagent products need to be examined for the presence or absence of particular species. In addition, obtaining good analytic results often requires that the dead volume associated with valving and tubing be extremely small. Examples of processes which would benefit from a micro-fluidic system are immunoassay tests, or DNA tests for forensic applications, infectious or genetic diseases or screening for genetic defects.xe2x80x9d
U.S. Pat. No. 6,146,103 for micromachined magnetohydrodynamic actuators and sensors to Abraham P. Lee and Asuncion V. Lemoff, patented Nov. 14, 2000 provides the following background information: xe2x80x9cMicrofluidics is the field for manipulating fluid samples and reagents in minute quantities, such as in micromachined channels, to enable hand-held bioinstrumentation and diagnostic tools with quicker process speeds. The ultimate goal is to integrate pumping, valving, mixing, reaction, and detection on a chip for biotechnological, chemical, environmental, and health care applications.xe2x80x9d
U.S. Pat. No. 6,382,254 for a microfluidic valve and method for controlling the flow of a liquid to Zhihao Yang and Ravi Sharma, issued May 7, 2002, provides the following background information, xe2x80x9cMicrofluidic systems are very important in several applications. For example, U.S. Pat. No. 5,445,008 discloses these systems in biomedical research such as DNA or peptide sequencing. U.S. Pat. No. 4,237,224 discloses such systems used in clinical diagnostics such as blood or plasma analysis. U.S. Pat. No. 5,252,743 discloses such systems used in combinatorial chemical synthesis for drug discovery. U.S. Pat. No. 6,055,002 also discloses such systems for use in ink jet printing technology. Valves and pumps are the two most fundamental components in controlling the fluid dynamics in a microfluidic system. Various efforts have been made to build miniature valves and pumps for microfluidic systems by micro machining silicon. Several valves and pumps have been disclosed using mechanical actuators, such as piezoelectric actuators or spring-loaded magnetic actuators. Examples of these are disclosed in U.S. Pat. Nos. 6,068,751; 5,171,132; 5,272,724; UK Patent 2,248,891, and European Patent 568,902. However, there are problems with these mechanically actuated microfluidic devices since they are complex in design, difficult to fabricate and suffer from a lack of mechanical durability and reliability. In addition, these valves are prone to leak because there are problems in producing a good seal. These problems generally result in the high cost, low productivity, and inoperability of these microfluidic devices. The compatibility in fabrication of the microfluidic devices with the procedure of semiconductor chip manufacturing industry is another important issue in achieving low cost microfluidic systems with mass production. In addition, for those more sophisticated microfluidic systems, a complex micro-valves and pumps system is often necessary to regulate the liquid in the devices. Therefore, an on-chip integrated circuit to control the individual valves and pumps is highly desired. This also requires the microfluidic devices to be compatible with IC fabrication such as the Complementary Metal Oxide System (CMOS) fabrication in the semiconductor industry.xe2x80x9d
Features and advantages of the present invention will become apparent from the following description. Applicants are providing this description, which includes drawings and examples of specific embodiments, to give a broad representation of the invention. Various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this description and by practice of the invention. The scope of the invention is not intended to be limited to the particular forms disclosed and the invention covers all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the claims.
The present invention provides a hydraulically amplified microelectromechanical systems actuator. A piece of piezoelectric material or stacked piezo bimorph is bonded or deposited as a thin film. The piece is operatively connected to a primary membrane. In one embodiment the piezoelectric material is Lead Zirconate Titanate (PZT). A reservoir is operatively connected to the primary membrane. The reservoir contains a fluid. A membrane is operatively connected to the reservoir. In operation, the microelectromechanical systems actuator utilizes the piezoelectric material, the primary membrane, the reservoir which contains a fluid, and the membrane to provide a microelectromechanical systems actuating method. Energizing the piezoelectric material causing the piezoelectric material to bow. The bowing of the piezoelectric material causes movement of the primary membrane. Movement of the primary membrane results in a force in being transmitted to the liquid in the reservoir. The force in the reservoir causes movement of the membrane. Movement of the membrane results in an operating actuator.
The invention is susceptible to modifications and alternative forms. Specific embodiments are shown by way of example. It is to be understood that the invention is not limited to the particular forms disclosed. The invention covers all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the claims.